1. Field of the Invention
The present invention relates to the field of a joint synthetic fuel formula for jet, rocket, or diesel engines, which contains a blend of high density synthetic (HDS) and low density synthetic (LDS) fuels.
2. Description of Related Art
Modern civilization is heavily dependent on crude oil for producing chemical feedstocks and petroleum fuels typically used in combustion engines. Due to the recent increase in demand for fuel from around the world, and the limited production of crude oil, there has been an increase in the price of liquid transportation fuels. In order to increase production of liquid fuel, low cost alternative fuels are needed to meet the ever increasing demand.
There is a vast amount of prior art available regarding non-fossil fuel denoted as carbonaceous feedstocks that can be used for the production of synthetic transportation fuel. Some of the more common carbonaceous feedstocks are coal, biomass, and solid municipal wastes.
The Coal, biomass and carbonaceous waste can be converted to a gaseous or liquid fuel by processes commonly referred to as pyrolysis and also by gasification and subsequent reforming by catalytic molecular synthesis.
Pyrolysis, or more specifically Low Temperature Carbonization (LTC), results in the chemical decomposition of organic materials such as biomass, solid waste or coal. LTC is accomplished by heating in the absence of oxygen. The Karrick process is an example of the pyrolysis of coal, but this process also results in retaining the desired cycloalkane ring structure necessary for HDS. Fuels produced by LTC typically have a density higher than normal for jet and diesel fuel.
In gasification, organic molecules from solid feedstocks are chemically degraded into smaller molecular weight molecules, known as producer gases, synthetic gas or syngas. Syngas is a mixture mainly consisting of carbon monoxide (CO) and hydrogen (H2) that may be used as a fuel formulation feedstock. Syngas can be processed into liquid fuels (such as, gasoline, diesel, jet fuel, etc.) by the Fischer-Tropsch (FT) synthesis process. Fuel produced by this method is known as Synthetic Paraffinic Kerosene (SPK) fuel. Fuels made from this process have a density lower than petroleum jet and diesel fuel. Thus, SPK is classified as LDS fuel for the purpose of the invention described herein.
A significant effort is under way to certify FT synthetic fuels, SPK, for use in U.S. and international aviation fleets. However, because the majorities of SPK are linear alkanes which do not contain highly branched alkanes or aromatic compounds containing high energy content per molecule. SPK lack certain properties suitable for jet and diesel fuels, e.g. seal swelling property for o-ring of engines. The thermal stability of SPK derived fuel is also lower than petroleum derived fuel which may contain aromatic compounds or highly branched alkanes. Consequently, SPK derived fuel is required to be blended with petroleum-derived fuel or other additives for the use of jet and diesel engines.
More specifically, by way of example, U.S. PreGrant Publication No. 2010/0108568 mentioned that straight run FT products have some inherent drawbacks in meeting Jet A-1 and/or Battlefield Use Fuel of the Future (BUFF) specifications, namely a high content of linear alkanes that result in a high freezing point and low temperature viscosity and a low aromatic content. The invention disclosed in U.S. PreGrant Publication No. 2010/0108568 provides a FT jet fuel refining process which includes a step to aromatize one or more of an FT syncrude fraction. The objective is to provide a SPK that meets Jet A-1/JP-8 and/or JP-5/BUFF specifications. The present invention is distinguished from this prior art because the invention utilizes commercially available fuel stocks obtained from the technically and commercially established chemical syntheses/processes.
ASTM International published a new fuel specification for aviation turbine fuels containing synthesized hydrocarbons, D7566, which is made of renewable feedstocks such as algae, jatropha-based, camelina-based SPK. This resulting fuel is virtually identical to jet fuel except it doesn't contain aromatic compound. The aromatic compound add density to the fuel and help maintain proper seal swell. Because of this lack of aromatics in bio-SPK, it is blended with 50% blend of petroleum-derived fuel that provides enough aromatics for adequate o-ring seal swell. The present invention is distinguished from this prior art in that a blend of two synthetic fuels derived from biomass, coal and carbonaceous waste are used instead of petroleum.
U.S. Pat. Nos. 7,683,224 and 7,560,603 disclose a method to make jet and diesel fuel that doesn't need to blend with petroleum-derived fuel to provide aromatics for adequate seal swell. Its method alkylates linear and lightly branched alkanes with aromatic moieties to make monoaromatics for use in jet and diesel fuels. A fuel has such monoaromatics having multiple desired properties such as higher flash point, low pour point, increased density, better lubricity, aerobic degradability, and additionally can deliver benefits in blendstocks. The present invention does not need extra synthesis in order to gain properties meeting jet and diesel fuel specification.
U.S. PreGrant Publication No. 2009/0013591 disclose an alternative gasoline, diesel fuel, marine diesel fuel, jet fuel, and flexible fuel compositions. The compositions include an alcohol and/or a glycerol ether or mixture of glycerol ethers, which can be derived from renewable resources.
In U.S. PreGrant Publication No. 20100011778A, a process of energy production is disclosed. The process includes integrating three or more energy production technologies such that a first byproduct of a first energy production technology is applied to a second energy production technology and a second byproduct of the second energy production technology is applied to a third energy production technology. The related art disclosed a process that integrates three or more energy production technologies in a series arrangement. Nevertheless, the invention disclosed here is a fuel composition that can be prepared by mixing and stirring of two products (HDS fuel and LDS fuel) from Karrick process and FT synthesis although the byproduct (CO or H2) from Karrick process can be applied to FT synthesis. The two products (HDS fuel and LDS fuel) can also be co-produced in parallel. In addition, the prior art does not claim composition of matter.
Although the aforementioned related art provide examples of a fuel or fuel blendstock for jet, rocket, and diesel engines, they involve more complex synthesis or processes in order to produce the desired joint fuels. The present invention is directed at an improved fuel formula that results in a 100% joint synthetic diesel and jet fuel (JSF) using a blend of HDS and LDS fuels, which are commercially available or can be produced by well known processes currently available. JSF overcomes the shortcomings which were discussed above and/or other shortcomings in existing technology.